Physics Ontology

One map of physics, three ways in. Drill down on any quantity to see its units, the equations it lives in, and how its values span the universe.

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Fundamental Constants

Planck Constant

Quantum of action; links photon energy to frequency (E = hf).

SI unit

joule second (J·s)

Dimension: [ ML2T−1 ][\,M L^2 T^{-1}\,]

Other units

  • joule second (J·s)

Defined value

Fixed constant from the A-level data sheets.

6.63 × 10-34 J·s

A-level value

Appears in 3 equations

Planck–Einstein Relation
E=hfE = h f
de Broglie Wavelength
λ=hp\lambda = \dfrac{h}{p}
Photoelectric Effect
Ek=hf−ϕE_k = h f - \phi

Associated scientists

Max PlanckAlbert EinsteinLouis de BroglieRobert Millikan